#include <stdio.h>

void fun_1(){
    printf("fun_1\n");
}
double fun_2(){
    return 3.14;
}
int fun_3(){
    int a = 1;
    int b = 2;
}
int fun_4(){
    return 20.89;
}


int main(){
    fun_1();
    printf("fun_2:%lf\n", fun_2());
    printf("fun_3:%d\n", fun_3()); // 返回一个不确定的值
    printf("fun_4:%d\n", fun_4());


    return 0;
}